Yeah I'm wondering if I should get a snail for my 10 gal filtered tank with my three female bettas. Last time I had a snail was a few years ago, and it seemed to "rot" it didnt move and just like....died. So can anyone tell me any suggestions on what i should do?
1. Can the snail produce any secretions that can harm my fish?
2. What the heck does a snail eat!?
3. Any other ideas on a weird creature for my tank?

For starters a Betta sorority (female only tank) should have about 5 females, after that there isn't room for much else.

Snails can be tricky additions, or simple. It depends on the snail. Snails eat whatever they want, usually algae or left over food. For the most part they will find what they need on their own but adding the occasional algae wafer is a good idea.

Is the tank divided? If not you have a number of other options.

The simpler option is Shrimp. Some Ghost shrimp can be fun, basically take the same care as a snail but I've found they aren't as ... odd ... as snails can be. You could also do a snail AND shrimp.

Platies. Platies are great fish in general, you'll need about 3 but they have been known to eat algae and are very peaceful.

African Dwarf frogs. I love my froggies. They take the same care as a Betta and are awesome.

However I will reiterate that if the tank isn't divided you should have 5 females. If it is divided then Platies are out.